//one dimensional array as grid
var grid = [];
var numCols = 5; 

function get(row, col){
	return grid[row*numCols + col];
}

function set(row, col, value){
	return grid[row*numCols + col] = value;
}

//one dimensional array as grid with stride 
//example;  rgba pixel data
function getPixel(x, y){
	var index = (y*imageData.width + x) * 4; //4 integers for RGBA
	var red = imageData[index];
	var green = imageData[index+1];
	var blue = imageData[index+2];
	var alpha = imageData[index+3];
	var alphaPrcnt = alpha/255; //0-1	
	
	var rgba = (red << 24) + (green << 16) + (blue << 8) + (alpha);
	return rgba;
}